Sewer lines, water lines and other types of buried pipelines can develop leaks over time. These leaks are a result of decaying materials such as the clay used in the construction of the pipeline, obstructions which may clog a line, chemical exposure or crushing due to overburden pressure due to the inferior materials used in very old pipelines. Many older lines require repair to prevent exterior leaking and possible ground water contamination. Additionally, without proper repair ground water can infiltrate into the broken sewer lines, thus causing significant increase in the volume of throughput and the expense of chemicals and other materials used for treatment of the sewer water.
Repairing leaking sewer lines and other forms of fluid transmission lines is very expensive due to the previous necessity of digging a trench from the surface to physically remove the pipe. The removal and replacement of this pipe from the surface is time-consuming, expensive and not practical in many old commercial and residential neighborhoods due to narrow alleyways, heavy traffic and the volume of pipe located below existing buildings or other obstructions.
Thus, "trenchless technology" was developed which utilizes machinery and methods of repairing sewer pipe and other buried transmission lines from the inside-out. This process eliminates the need for digging expensive trenches aboveground. In brief, the existing main pipeline is repaired by installing a plastic liner which is inserted into the existing pipeline. The plastic liner is then bonded to the internal surface of the existing pipeline by heating or other methods. The existing lateral service lines which feed the main pipeline are then located by the use of a robotic device with an optical camera. Once identified, a hole is drilled by the robot mechanism into the existing pipeline, thus providing access into the lateral service line.
Unfortunately, the hole drilled into the existing lateral service line does not provide a satisfactory seal, thus permitting significant volumes of groundwater, as well as plant roots, dirt and other foreign objects to infiltrate the main pipeline at the junction point between the lateral service line(s) and the main pipeline. Additionally, contaminants within the main pipeline can potentially leak and pollute the adjacent groundwater. Thus, a need exists to provide a reliable patching mechanism to seal the junction point between the lateral service line and main pipeline which can be operated remotely and which functions from within the small internal confines of the main pipeline.
Others have attempted to seal the junction between the main pipeline and lateral service line, but known approaches have considerable disadvantages. U.S. Pat. No. 5,329,063 to Endoh exemplifies a technique where a flexible tubular liner is inserted into a lateral line so that the entire lateral line receives a lining. Air or liquid pressure is needed to insert the reversed flexible liner into the lateral. Once the liner is extended by the air pressure from the junction to the other end of the lateral pipe, access to that other end of the lateral line is required to cut away any excess liner. In this way, the entire lateral pipe is lined from one end to the other.
As those skilled in the art can appreciate, installing a flexible liner in a lateral service line is very time consuming and difficult. The apparatus required for installation has many moving parts and is complex to operate. Additionally, access to the distal end of the lateral line (i.e., the end away from the main pipeline) is needed to cut away the excess liner. The complex setup required makes sealing the junction of the main pipeline and lateral service line both time consuming and expensive.
Further, the results achieved by the flexible liners are erratic because the lateral service line is not a controlled environment. For example, the lateral may contain debris which will obstruct the flexible liner so that when the liner is hardened, the obstructions will permanently interfere with the flow in the lateral line. Additionally, the environment in which the flexible liner must be installed into is subject to wide temperature swings which further encumbers achieving consistent results. Therefore, there is a need for quickly and inexpensively sealing the junction between a main pipeline and lateral service line with consistent results. This is especially needed in situations where it is difficult or impractical to obtain access to the distal end of a lateral service line. Further, there is a need for quickly curing the epoxy, glue or resins which are used as a sealing medium between the underground patch and the lateral pipeline and main pipeline.